Method of curing concrete



Patented May 7, 1935 UNI D.

METHOD OFCONCRETE I Arthur A."Johnson, Great mean. Y;

No Drawing. "Application 15, a 1153 -1 35 9 Claim; (019254154) insuificient hydration or incomplete chemical reaction will result, in which case the concrete will not possessftherequisite strength o'rjiiensity and will, besubject to cracking and scaling. Although sufficient water present 3 when the concrete is poured yet unless specialprecautions fare' taken evaporation of the water-lwillltalge place after pouring and duringthecuringip er riod with 1. the 7 resulting disadvantages-ofmen tioned. For this reason it has been proposedby several workers in this art to coat the concrete with a wateriimpervious coating of "a permanent orf temporary character shortly iollowing; the pouring of the "concrete whereby to efiectively seal the surface against escape of moisture.

' It is a, principal object of the present inventiont to provide a methodof curing concrete employing an improved water impervious coating, Itis also an object to provideanimprov'ed 'coating..composition; for this purpose. Heretofore a substance .widely proposed for the' curing Q c e e h een-an s a t o h r milar bituminous substance in the form. of j a wateremulsion, lfhe coating formed from this mixture has certain disadvantages which it is fdesiredto'overcome.

My resent inv t i r based m "th d covery that'new" and desirable qualities are parted to bituminous curing agentsfor curing concrete by the incorporation therein of rub- Qber, preferably in the form of rubber, latex. I .find that a mixture of a bituminousemulsion, for example, and latex in suitableproportions produces a coherent film which while Very thin isnevertheless absolutely impervious, f or all :practical purposes," to passage of moisture, a resultwh ichis not completely obtained whenthe V concreteis coated with ordinary water iemul- *sion's of bitumen. My invention also provides a film of greatelasticity and toughness-and one which furthermore willnot flow under the'heat of the sun (thus leaving parts of the concrete exposed) as is apt to be the case with the coating formed from the ordinary bituminous emul-, sion. Neither will the film tend to disintegrate and fiake ofl? due to oxidation and the eifects of strongsunlight as may be the case with coatings consisting entirely of bitumen. A quality by the film 'produced byme that it;may be, peeled 011, Owing to .thedark color of th this n a va ta ed h o The film further has great coherency and-the :liguid'qcompositmn vhasahigh covering power whereby irregularities: in the surface are efiectively coated Beeause of the' elasticity oi the v it ;W i1 1 retain its; impervious characteris- V tics irrespective of expansion and contraction,

vibration or .fiexure-oi thesurface to which it is applie d.'-: ,I have furthe11iound that the presence oi the latex increases the stability of the b11311? minous emulsion andthus overcomes a runner disadvantage of the ordinary bituminous emulsion whichis its tendency to settle out just betforeflapplicationa I jInr preparing my; new

bituminous remulsionyinjwater'in which isfim kompitioii I mien ably-employalmixtureconsisting essentifllyofa size and the water then added together-"with sodium holeate or other soluble 1 soap, 'gelatine,

caseiziffetci', asa proteetive colloid; Theentire mixture is thenfpassed thr ugh a colloid mill to'ior'nia suitable emulsion.

Suitableproportionsof mixtures A and B are now,mixed together,. as'fo17 examplemixture A .75 parts and mixtureB 25 parts byvolume.

,JIhe sodiumU-benzoate is-useful to insure the a 7 os t n. t e amoun used, v y ng dependingv .upon'" climatic conditionsix Thus in hotfand somewhat humid weather the factor of fermentation must be carefullytakeninto account,

particularly since when the mixture is spread upon a surface so as to form a film, the ammonia with which the latex was originally preserved evaporates, thereby leaving the film 'for'med without a preservative. On the other of 2% ofthe weight of the latex. The presence of the shellac may under some circumstances be useful in that it decreases 'the period of tackiness following the spraying of the mate-' rial. The sulphur acts to vulcanize the :rubber when the film is subjected to the heat of the sun and renders the film somewhat tougher.

well known rubber accelerators and activators may be added but'usually this is unnecessary; In some instances small amounts of" fillers may be added to the compound, such for instance as clay, talc, gypsum, feldspar, bentonitacarbon or lamp black, etciusually infproportions' of from two to five per cent of filler." By rubber latex-I mean; not-only the milky sap or juice of -the specie's 'Heven 'brasili eneis, but various other rubber bearing plants.

While the use of rubber in the form of latex is preferred, my invention also contemplates using artificial rubber dispersions. For the-bituminous part of the compoundfI prefer to'use a'native asphalt, but other asphaltic emulsions may be substitutedifof a suitable character. In use vthe improved composition is sprayed upon or otherwise applied to the surface of .1 the concrete to be and is allowed'to remain thereon untiltheen'd of the curing period, whereupon it may be removed therefrom' if desired by peeling or-otherwise.- Preferably the coating is applied immediately after pouring and before the concrete has begun to set. In some instances, however, the concrete during the in-' itial setting period of approximately 24 hours may instead be protectedby burlap as is well known or in any other suitable mannen after which the burlap is removed and my'coating applied for the remainder of the curing period which usually is consideredto last from two weeks to a month: T

Because of the black color of the coating, the property of the removability of the film taken with that of sufficient tenacity to thoroughly protect the surface against the escape of moisture is particularly valuable since otherwise the black coating must be allowed to wear off, which process somewhat detracts from the appearance oftheroadway." I In contradistinctio'n to a filr'n made of ordinary asphalt which is hard and brittle when cold and fluid when heated, my improved film'although .sists incovering the exposed surfaces of the concrete to be cured with a water emulsion of bitumen having rubber latex incorporated therecontaining up to'75% or more asphalt possesses true elasticity and forms an absolutely impervious film. In addition, owing to the comparative- 1y low rubber content, the improved'compound has the advantage of cheapness and of low viscosity so as topermit of applicationby simple spraying. The addition of the later appears to act as a protective against the disintegration of the film due to the effects upon the asphalt of oxidation and actinic light rays. Asphalt, when spread in thin films and exposed to sunlight and air is ordinarily subject to serious deterioration from these causes, and this is very noticeable when ordinary bituminous emulsions of asphalt are used .for curing concrete, particularly concrete roadways where the exposure to sun and air is most pronounced. While an ordinary asphalt emulsion curing coating may be seriously disintegrated before the curing period is comlfclaim: I Satisfactory results may, however, be obtained without its use. If desired, small quantities of 1. The method of curing concrete, which consists covering the exposed surfaces of the concrete to be cured with a mixture of bitumen and rubber. 2. The method of curing concrete, which consists 'in covering the exposed surfaces of the concrete during the curing period with a mixture of bitumen and rubber latex."

3; The method of curing concrete, which consists'in covering the exposed surfaces of the concrete with a mixture of bitumen, rubber and sulphur to produce vulcanization of the rubber.

4.; 'I'he method of curing concrete which consists in covering the exposed surface of the cone cretebeforethe same, is set with a mixture of bitumen and rubber latex adapted to form a substantially moisture impervious film so as to retain within the concrete substantially the entire initial water content thereof during the curi s p d-, 1 5'. A method of curing concrete which consists in; covering. the exposed surface of the freshly poured concrete with a layer of burlap or' the like, removing the burlap after an initial period of settingand before the curing of the concrete is completed and then coating the surface of. the concrete with a film containing bitumen and rubber. g 1 5. The method of curing concrete which consistsin coating the exposed surface of the concrete with a mixture containing the following ingredients bitumen, rubber latex, and a preservative.

7 Themethod of. curing concrete, which consists in covering the exposed surfaces of the 8 Themethod of curing concrete, which consists in covering the exposed surfaces of the concrete to be cured with a water emulsion of native vasphalt having rubber latex incorporated therein. 1 I V 9. The method of curing concrete, which conin, in which the rubber latex is present in the proportion of approximately25%.

ARTHUR A. JOHNSON.

pleted, this is not true of my improved curing 

